Fundamental Physical Quantities of a Flowing Gas

Question 1

What are the Four Fundamental Quantities in Aerodynamics?

Answer 1

• Pressure - Velocity - Density - Temperature

Question 2

What is pressure?

Answer 2

The normal force per unit area exerted on a surface due to the time rate of change of momentum of the gas molecules impacting on that surface.

Question 3

What is dA?

Answer 3

An incremental area around a point B

Question 4

What is dF?

Answer 4

Force on one side of dA due to pressure

Question 5

What are common units of pressure?

Answer 5

-Newtons per square inch - dynes per square centimeter - Pounds per square foot - atmospheres

Question 6

What is density?

Answer 6

The mass of a substance per unit volume

Question 7

What is the symbol for density?

Answer 7

ρ

Question 8

What is dv?

Answer 8

Elemental volume around a point

Question 9

What is dm?

Answer 9

Mass of gas inside of dv

Question 10

What is temperature?

Answer 10

The measure of the average kinetic energy of the particles in the gas. KE = 3/2kT k = 1.38 x 10^-23

Question 11

What are the two natural sources of aerodynamic force?

Answer 11

Pressure distribution on the surface

Shear stress (friction) on the surface

Question 12

What is the equation of state for a perfect gas?

Answer 12

p=ρRT

R is a specific gas constant.

Question 13

What is the density of air at standard atmospheric pressure and temperature?

Question 14

What is the density of air at standard pressure and temperature?